Valvular Heart Disease and Heart Sounds Flashcards
Valvular Stenosis
When the maximal opening area of a heart valve is reduced; substantially increases resistance to forward flow.
To maintain a constant output, the heart compensates by operating at progressively higher ejection pressures.
Structural changes of the heart: Pressure overload hypertrophy –> results in a thicker muscle wall of the chamber; capable of stronger contraction and greater force production.
Valve insufficiency
The valve loses its ability to close tightly because of damage to the valve leaflet structures; this allows blood to flow in both directions.
This increases the workload of the heart because a higher amount of blood must be pumped per minute in order to maintain normal output.
The hart enlarges itself to accommodate more volume within its chambers (eccentric hypertrophy); more blood can be ejected with each beat.
Pressure overload
Causes walls of the left ventricle to thicken, the chamber size to stay normal and the pump function to be preserved.
These changes are produced by an increase in the diameter and volume density of myocytes in the wall of the left ventricle.
Volume overload
From insufficiency of valve.
The left ventricle responds with enlargement of the volume of the chamber.
Myocytes lengthen themselves induced by the stretch of the increased volume of the chamber; they function at normal levels of performance, they just accept larger volumes of blood more easily.
These adaptive changes can leave patients with no symptoms for long periods of time; but muscle eventually runs out of ability to further hypertrophy, heart muscle will begin to fail and die and patient will develop heart failure.
Aortic Stenosis
CAUSES:
congenital bicuspid valve
Rheumatic heart disease (inflammatory condition)
senile calcific aortic stenosis
MECHANISM:
Rheumatic heart disease is the only one that causes direct injury and inflammation of valve.
Sheer stress on leaflets may initiate injury, which can set off an injury inflammation cycle in the leaflet.
Early in the process, there are areas of oxidized LDL, enzymes, and macrophages.
Progression, growth factors and reg proteins transform some cells from fibrocytes into osteoblasts.
Further calcium nodules form, stiffening up leaflets, which increases force required to open valve; get higher and higher flow speeds to try and maintain volume with each heartbeat with more stenosis.
SYMPTOMS: Exertional angina pectoris, exertional syncope (reduced heart ability to increase cardiac output during exercise, reflexes of left ventricle to decrease pressure by causing vasodilation), heart failure (ability to heart to fill when walls are thickened is impaired, increase filling pressures translate back to the lungs causing congestion).
TREATMENT: prosthetic valve
Aortic insufficiency
CAUSES: Rheumatic heart disease, destruction of leaflets by endocarditis, bicuspid valve, abnormalities of the aorta causing dilation of the annulus of valve (insufficient closing of valve).
SYMPTOMS: Shortness of breath with exertion
TREATMENT: prosthetic device or repair/reinforcement with a Dacron conduit.
Mitral Stenosis
CAUSES: mostly caused by rheumatic heart disease; causes fusion of portions of mitral leaflet apparatus, thickening of other parts of mitral valve, and calcification and retraction of leaflet substance.
SYMPTOMS: Limits the ability of the left ventricle to fill=increase pressure in the left atrial chamber; these high pressures are translated back to the lungs and congestion occurs creating cardiac dyspnea:
Stage 1: High pressures within capillaries in lungs causes fluid from blood to leak out into space around capillaries into interstitial space, but lymph system can take care of this; lungs are somewhat heavier.
Stage 2: Lymph system is overwhelmed and fluid starts filling up in interstitial space.
Stage 3: Fluid invades air sacs; air sacs collapse, ending their ability to exchange gas; patient is grasping for breath and will lead to death if not corrected.
EVERY TIME A PERSON BECOMES SHORT OF BREATH DUE TO CARDIAC CAUSE, THIS IS THE SEQUENCE OF EVENTS THAT OCCURS.
TREATMENT: Can open valve using a balloon catheter or cut it open at surgery, prosthetic device.
Mitral insufficiency
CAUSES: rheumatic heart disease (scar the leaflets to reduce the size of leaflet present), mitral valve prolapse (leaflets are oversized and floppy and do not come together properly), papillary muscle or chord tendineae rupture (associated with heart attack), other processes of wear and tear which cause chronic calcification or scarring on leaflets to occur.
SYMPTOMS: acute sudden development of a large leak across mitral valve is a medical emergency, short of breath; chronic insufficiency can leave patient symptom free for a long time, once adaptive processes run out, shortness of breath, fatigue and side effects might occur.
TREATMENT: Surgical repair, prosthetic device.
Right sided heart valves
Pulmonic stenosis: mostly due to congenital heart problems
Congenital failure of leaflet formation, children.
Tricuspid valve stenosis: almost exclusively caused by rheumatic heart disease and much less common than mitral or aortic stenosis.
Tricuspid insufficiency: very common, primarily occurs as a secondary consequence of enlargement of the right ventricular or right atrial chambers.
Carcinoid heart disease: cancer with tumor that secretes serotonin-like substance into bloodstream and can cause changes in the right side of the heart; lungs filter out substance, so more drugs get to the tricuspid valve as it enters the bloodstream.
Heart Murmurs
Sound generated by turbulent flow of blood; when valve disease occurs, flow becomes turbulent and energy released can cause noise.
High pressure gradient=higher pitched murmur
Lower pressure gradient=lower pitched murmur
Valves are normally silent other than the opening/closing sound.
Heart sounds
The first heart sound is generated by deceleration of blood and closure of the mitral valve.
The second heart sound is generated by similar processes that close the aortic valve.
The third and fourth heart sounds tend to be associated with disease.
Third: rapid filling of the left ventricle after the mitral valve opens in the early phase of diastole when normally 70% of the blood flows into the ventricular chamber; peak of this filling in a diseased heart (abnormally large amount of blood or a higher than normal pressure).
Fourth: when the left atrium contracts and forces blood across the mitral valve into the left ventricle; if this force sends a sufficient amount of energy, a sound will be produced at the peak of flow.
Murmus
Aortic stenosis: diamond shaped murmur, turbulent flow in systole, nothing in diastole.
Mitral regurgitation (leaky); turbulent murmur in systole, nothing in diastole.
Aortic regurgitation (leaky); high pitched murmur in diastole that drops over time.
Mitral stenosis; low pitched murmur toward the end of diastole and also a little in the early part.
SAME TYPES OF MURMURS AND SHAPES ARE POSSIBLE ON THE RIGHT SIDE OF THE HEART.
Endocarditis
CAUSE: frequently a low-grade organism normally present in the flora of GI system or mouth; cause of bacterial endocarditis is never identified; most likely bacteria, fungal, inflammatory.
Tend to cause large vegetations on valves; organisms first manifest themselves often by embolization of the large vegetation.
SYMPTOMS:
